Lake gravel beach sedimentological variability, Milarrochy Bay, Loch Lomond, Scotland

Abstract

AbstractThe nature and environmental significance of variations in sedimentological parameters of a restricted-fetch lake coastal system (Milarrochy, Loch Lomond) are described in the context of climate change. Grain size characteristics of the beach, streams, cliffs and nearshore/offshore sedimentary environments are distinct, with variability being related to sediment supply, beach altitude and process conditions. Beach grain sizes range from silt to cobble, and are predominantly rounded discs and blades. There is an overall trend of offshore fining with increasing depth, beyond the mixed surf zone and clear limit of coarse sediment (coarser than -1 phi), resulting from dominant shore-normal process trends. Seasonal trends of water level fluctuation, sediment discharge and transfer from river to beach are important controls on local scale variability. The broader significance is that local physiography, sediment characteristics and supply strongly influence beach sedimentology and morphological response, even in the context of larger scale climate change. The record of sedimentological variability detailed here is significant for beach management projects and a better understanding of lake sedimentary facies within the Quaternary.